We term heat as energy of hotness, it makes  the object hot . We feel cold in winter, specially inside the room. But when we go outside in front of sunrays, then we feel  warm.   We term the temperature as the measurement of degree of hotness  or coldness.  This property indicates whether the substance is hot or cold. A high temperature informs us that the object is very hot. Beside it ice has very low temperature as  it is called very cold.

We measure the temperature by a device which we term as thermometer.  This has marking of scale on it which we read as temperature.  Each division of scale is degree of hotness.  The thermometers are mercury  thermometer. In some thermometer the scale marking is from 0° to 100°. This scale we term as  Celsius  scale. We use this Celsius scale in measuring  weather temperature or measuring  temperature in laboratory. Another measuring scale of  hotness is Farenhit.  It has marking from 32° to 212° .  Total 180 scales are there. So, when  we supply a particular amount of heat  to the thermometer bulb  consisting  mercury, then the mercury expands due to hotness and gets rises in the glass tube of thermometer. In this way we can use this fact to measure the temperature.


Step 1 Firstly,  we must wash the clinical thermometer with an antiseptic  solution and if in case, the antiseptic solution is not available, we should wash it with water.

Step 2 We must hold the clinical thermometer with care in hand. We should jerk the mercury of thermometer in such a way that mercury in  the clinical thermometer tube goes down under  95°F or  35°C.

Step 3 Now, we should put the clinical thermometer bulb under the tongue of the patient for about one minute. Then we take out the clinical thermometer from patient’s mouth.

Step 4 In order to read the temperature, we should hold the clinical thermometer horizontally in our hand and rotate it slowly.  If we observe the bigger image of mercury inside the clinical thermometer tube, then we can understand a position of the tube. Now,  it is the time to read the temperature reading due to hotness on the  glass along with the top portion of mercury thread.


Qs1:  If we construct a house in a coastal area, we should place the windows in which direction? why?

Ans1: Windows should preferably towards the sea beach so that the sea breeze coming from the sea keeps the house cool during the day time.

Qs2: The mercury  level does not change even if the clinical thermometer is taken out from the mouth of the patient. Explain the statement on hotness, why?

Ans2: Because of the  kink present in the clinical thermometer, the mercury does not fall or rise.

Qs3:  Suppose  we heated a pan on fire, if we remove it , the pan becomes cooled. Why is it happened?

Ans3:  If we remove a pan from the source of heat, then it releases heat by radiation process around itself and becomes cool.

 Qs4:  In which process of heat requires no medium.

 Ans4:  In the radiation process medium is not required.


Qs5:  If we observe a thermometer containing mercury inside, we see the mercury level increases in contact of hot object. Why is it happened?

 Ans5:  In contact of hot object,  mercury  expands as it is metal.  That is why  levelof mercury increases.

Qs6: The radiators in cars are painted black. Explain why?

Ans6: Since, the black bodies are better radiators as black absorbs heat properly , so due to this reason, we use to paint the car radiators black.

Qs7: Why should we like to take two thin blankets than one thick blanket in winter.

 Ans7:   There is an air gap in between two thin blankets . This phenomenon  does not allow heat pass out from the body and it is not as such as in case of one thick blanket.

Qs8:  We should not hold the thermometer bulb while observing temperature, why?

 Ans8: We should not hold the bulb of clinical thermometer when we want to read the level of mercury. Because  the level of mercury increases due to hotness while touching from the actual reading by our body temperature.

Qs9:  Imagine there are two different colored tent in a tourist place. One tent is made up of black color material, another with white color cloth.  In a hot summer afternoon in which tent will you want to rest? Which tent will you prefer in winter? Give reason.

Ans9: We will  like to stay in white fabric tent in case of summer because it reflects all the radiations from the sun and keeps us cool inside the tent.

But in case of winter, we should not use white fabric tent, we should use black fabric tent as it absorbs all colors of light from the sun and keeps us warm inside the tent.


Qs10: Study  the following statement “  when we apply  heat at the bottom of the water vessel, then the bottom part becomes heated fast than that of top”: justify your statement .

 Ans10:  The particles of water at the bottom become hot and lighter. So it comes up in the middle.  For this reason, upper portion cold water particles which are heavy also settle down at the bottom. In this way heat flows in convection mode and make the water hot.  If we apply heat at the top, then  hot and lighter water particles are not moving. Only upper surface of water is heated.  As we know that  water cannot conduct heat properly. So, bottom part of water remains cold.

 Qs11:  Why do we serve hot tea or coffee or soup in china clay cup or bowl?

Ans11: Generally we serve hot tea or coffee in china clay cup or pot. Because china clay material  is a poor conductor of heat. This material does not allow heat to be released outward, and keeps the tea hot for long time.

Qs12:  What is the reason  that we cannot measure clinical thermometer  of hotness in case of high temperature?

 Ans12:  There is a limited range of temperature in Clinical thermometer, i.e. 35°C to  42°C OR  95°F to 105°F. Mercury is dangerous for living organism. So, by using mercury in clinical thermometer for measuring high temperature may cause an accident by breaking. That is why we must avoid mercury temperature to get high temperature.

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